The invention relates to biomedical articles. More specifically, the invention relates to hydrogel biomedical articles formed from crosslinkable macromonomers (referred to herein as macromers).
Poly(vinyl alcohol) (PVA) hydrogels have been proposed as medical devices, however many of the proposed devices have suffered either from inferior mechanical strength or from tissue damage resulting from the use of chemical agents to harden them. To overcome this problem, Tanabe (U.S. Pat. No. 4,734,097) and Ku (U.S. Pat. No. 5,981,826) have proposed the use of cryogels. However these cryogels are not covalently crosslinked and hence are not suitable for long-term contact with tissues and cannot be formed in vivo. Bao (U.S. Pat. No. 5,047,055) proposes the use of PVA hydrogels as a prosthetic nucleus for a vertebral disc but he also does not form these hydrogels by covalent crosslinking, rather he crystallizes a solution of PVA at a temperature of −10° C. or below. Nambu (U.S. Pat. No. 4,808,353) makes artificial biological membranes of PVA solutions by a similar freezing process. Capecchi (U.S. Pat. No. 5,108,428) describes UV cured PVA hydrogel cornea implants, but these are first pressed into sheets at 191° C. for two minutes and then solvolyzed in 10% methanolic ammonium hydroxide before final application.